[TYPO3-core] RFC #11895: Cookie detection in new t3skin login screen fails for certain cirumstances

[Steffen Gebert]

This is an SVN patch request.

Type: Bugfix

Bugtracker references:
http://bugs.typo3.org/view.php?id=11895

Branches:
Trunk

Problem:
With changeset 5899 (0011370) a new t3skin login screen has been committed  
to trunk.

Coming with this changeset is a cookie detection [1] implemented in  
JavaScript. If this detection thinks that cookie usage is not possible  
(cookies not allowed), an image is shown ("ACTIVATE COOKIES, PLEASE")  
instead of the login form.

However, this detection fails for following condition (at least in FF3.5):
- cookies are generally disallowed and
- certains domains are in a whitelist

If this condition is met (TYPO3 installation domain in whitelist),  
detection fails , the form is covered by an annoying image and login is no  
longer possible although cookies are accepted for this specific domain.


Solution:
Don't check navigator.cookieEnabled, but directly set testcookie.
Furthermore add an ignore-link (if there might still be cases, where check  
fails)

Notes:
Thanks to Marcus Krause for reporting.
You can deactivate cookies in firefox by setting
network.cookie.cookieBehavior = 2
in about:config



[1]
var cookieEnabled = (navigator.cookieEnabled) ? true : false;

if (typeof navigator.cookieEnabled == "undefined" && !cookieEnabled) {
     document.cookie = "testcookie";
     cookieEnabled = (document.cookie.indexOf("testcookie") != -1) ? true :  
false;
}
if (cookieEnabled) {
     document.getElementById("t3-login-form-fields").style.display =  
'block';
}
else {
     document.getElementById("t3-nocookies-error").style.display = 'block';
}